读写普通文本文件：

public class MainActivity extends Activity {
        EditText edit;    @Override    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        edit = (EditText) findViewById(R.id.edit);        BufferedReader reader = null;        FileInputStream is;        StringBuilder content = new StringBuilder();        try {
                is = openFileInput("TestFileWrite");            reader = new BufferedReader(new InputStreamReader(is));            String line;            while ((line = reader.readLine()) != null) {
                    content.append(line);            }        } catch (Exception e) {
                e.printStackTrace();        } finally {
                try {
                    if (reader != null) {
                        reader.close();                }            } catch (IOException e) {
                    e.printStackTrace();            }        }        edit.setText(content.toString());        edit.setSelection(content.toString().length());    }    @Override    protected void onDestroy() {
            super.onDestroy();        String text = edit.getText().toString();        BufferedWriter writer = null;        try {
                FileOutputStream os = openFileOutput("TestFileWrite", Context.MODE_PRIVATE);            writer = new BufferedWriter(new OutputStreamWriter(os));            writer.write(text);        } catch (Exception e) {
                e.printStackTrace();        } finally {
                if (writer != null) {
                    try {
                        writer.close();                } catch (IOException e) {
                        e.printStackTrace();                }            }        }    }}

使用SharedPreferences对象持久化数据

// SharedPreferences pref = this.getPreferences(Context.MODE_PRIVATE);  //文件名即Activity类名// SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(this);  //文件名即主类包名_preferences        SharedPreferences pref = this.getSharedPreferences("filename", Context.MODE_PRIVATE);Editor editor = pref.edit();editor.putBoolean("remember_password", true);editor.putString("username", "admin");editor.putString("password", "123");// editor.clear();editor.commit();pref.getString("name", "no_name");pref.getString("password", "no_pass");pref.getBoolean("remember_password", false);

文件存储位置：/data/data/主类包名/ 目录，主类包名，不一定是当前包名。